Which of the following is a first step in mechanism of heterogenous catalysis?

Which of the following carboxylic acids has lowest boiling point?

For the reaction, $$2 \mathrm{~A}+\mathrm{B} \rightarrow 2 \mathrm{C}$$, rate of disappearance of $$\mathrm{A}$$ is $$0.076 \mathrm{~mol} \mathrm{~s}^{-1}$$. What is the rate of disappearance of $$\mathrm{B}$$ ?

Which of following is an example of cross-linked polymers?